1. Technical Field
The present invention relates to metal powder having open and homogenous pores.
2. Background Arts
Porous metal powder is sintered into various metal products such as a catalyst, an electrode, a filter and an oil impregnated sintered bearing. The metal powder useful for such applications has many pores, the pores being very important for the metal products to function. Recently, it is required to raise the performance of the metal products, for which porous metal powder qualified better is demanded. For example, it is required to develop porous metal powder modified to have homogenous and open pores.
There have been various methods for preparing porous metal powder. One way is disclosed in the U.S. Pat. No. 3,888,657 to heat starting metal to form pores. Also, another way is disclosed in the Japanese patent No.52-37,475 to oxidize and then reduce starting metal to form pores. The latter way, commonly referred to as an oxidation-reduction method, is remarked as a method for preparing metal powder having many fine pores.
Present invention provides a novel oxidation-reduction method improved for preparing metal powder having fine and homogenous open pores.
There is provided a method for preparing porous metal powder in which a starting metal is oxidized and then reduced followed by that thereby obtained block metal body is milled. According to the present invention, the starting metal is oxidized in the presence of chlorine and/or chloride.
The reduced block metal body according to the present invention comprises prismatic particles entangled like a root so that the pore formed in the metal powder is open.